Gamma voltage driving circuit, source driving module, and liquid crystal panel

ABSTRACT

The present invention discloses a Gamma voltage driving circuit, which comprises a voltage dividing resistor string, which comprises 2 n  resistors connected in series sequentially, used to divide a reference voltage into 2 n  Gamma voltages; wherein, n is an integer not less than 1; a reference voltage module, which provides the reference voltage for the voltage dividing resistor string; a voltage selecting module, which is used to selectively output one of the 2 n  Gamma voltages. The reference voltage module comprises a first reference voltage and a second reference voltage, the first reference voltage is coupled to one end of the voltage dividing resistor string, the second reference voltage is coupled between the 2 n /2-th resistor and the (2 n /2+1)-th resistor; wherein, the voltage selecting module comprises 2 n −1 transmission lines, which respectively connects the voltage dividing nodes of the first to (2 n /2−1)-th resistors and the (2 n /2+1)-th to 2 n -th resistors in the voltage dividing resistor string to a output terminal; and each transmission line is provided with n−1 switching units.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the technology fields of liquid crystaldisplay, and in particular to a gamma voltage driving circuit, a sourcedriving module, and a liquid crystal panel comprising the source drivingmodule in the liquid crystal display.

2. The Related Arts

Liquid crystal display (LCD) is a flat and thin display device. It isconsisted of color or monochrome pixels with a certain amount, which isplaced in front of the light source or the reflector. Liquid crystaldisplay has low power consumption, high image quality, small size, andlight weight, so it is favored to become the mainstream of display. Theexisting liquid crystal display is mainly thin film transistor (TFT)liquid crystal display, and the liquid crystal panel is the maincomponent of the liquid crystal display.

FIG. 1 is a schematic view illustrating the structure of a liquidcrystal panel, which comprises an upper glass substrate 1, a down glasssubstrate 2, and a liquid crystal layer 3 between the upper glasssubstrate 1 and the down glass substrate 2. One side of the liquidcrystal layer 3 is provided with an ITO common electrode 4. The ITOcommon electrode 4 is connected to the Vcom voltage. The other side ofthe liquid crystal layer 3 is provided with multiple pixel electrodes 5.Each pixel electrode is connected to a Gamma voltage. The Gamma voltageis used to control the display grayscale of the liquid crystal panel.The voltage difference between different Gamma voltages and the Vcomvoltage results in different rotation angles of liquid crystal, whichforms the brightness difference. That is, the Gamma voltage divides thechanging process from white to black into 2^(n) equal parts.

For example, FIG. 2 is a Gamma voltage driving circuit according to theprior art, which comprises a reference voltage module 10, a voltagedividing resistor string 20, and a voltage selecting module 30. Thecircuit corresponds to 3 bit binary code, that is, the voltage dividingresistor string 20 divides the reference voltage into 8 Gamma voltageV1˜V8 (divide the changing process from white to black into 2³ equalparts), the voltage selecting module 30 selectively outputs one of theGamma voltage. The voltage selecting module 30 is consisted of multipleMOS transistors 301. In the 3 bit driving circuit, each transmissionline of the Gamma voltage provides with three MOS transistor, which istotal 8*3=24 MOS transistors. In FIG. 2, when it selectively outputs theGamma voltage V8, the corresponding binary code is (111), the voltageselecting module 30 turns on the MOS transistors b2, b1, and b0, andthen the Gamma voltage V8 connects to the output terminal. In thedriving circuit, when it utilizes 10 bit binary code, as shown in FIG.3, the voltage dividing resistor string 20 divides the reference voltageinto 1024 Gamma voltages V1˜V1024 (divide the changing process fromwhite to black into 2¹⁰ equal parts), the voltage selecting module 30totally needs 1024*10=10240 MOS transistors 301. A large number of MOStransistors increase the difficulty of the design of driver IC and theproduction process, which increases the costs.

SUMMARY OF THE INVENTION

In view of the lack of the prior art, an object of the present inventionis to provide a Gamma voltage driving circuit, which can reduce theusing amount of device, reduce the difficulty of the design of driver ICand the production process, and save the costs.

In order to achieve the above object, the embodiment according to thepresent invention adopts the following technical solution:

-   a Gamma voltage driving circuit, used to generate multiple Gamma    voltages, comprising:-   a voltage dividing resistor string, which comprises 2^(n) resistors    connected in series sequentially, used to divide a reference voltage    into 2^(n) Gamma voltages; wherein, n is an integer not less than 1;-   a reference voltage module, which provides reference voltage for the    voltage dividing resistor string;-   a voltage selecting module, which is used to selectively output one    of the 2^(n) Gamma voltages;-   characterized in that, the reference voltage module comprises a    first reference voltage and a second reference voltage, the first    reference voltage is coupled to one end of the voltage dividing    resistor string, the other end of the voltage dividing resistor    string is connected to the ground; the second reference voltage is    coupled between the 2^(n)/2-th resistor and the (2^(n)/2+1)-th    resistor, wherein, the value of the second reference voltage is ½ of    that of the first reference voltage;-   wherein, the voltage selecting module comprises 2^(n)−1 transmission    lines, which respectively connects the voltage dividing nodes of the    first to (2^(n)/2−1)-th resistors and the (2^(n)/2+1)-th to 2^(n)-th    resistors in the voltage dividing resistor string to a output    terminal; and each transmission line is provided with n−1 switching    units.

Wherein, in the voltage dividing resistor string, the first to(2^(n)/2−1)-th resistors divide the voltage value between the firstreference voltage and the second reference voltage into 2^(n)/2 Gammavoltages; the (2^(n)/2+1)-th to 2^(n)-th resistors divide the voltagevalue between the second reference voltage and the ground voltage into2^(n)/2 Gamma voltages.

Wherein, the 2^(n) resistors are equivalent resistance.

Wherein, the driving circuit further comprises a control module, whichis used to provide a control signal and a selecting signal for thevoltage selecting module; when the voltage selecting module receives afirst control signal and the selecting signal, the selecting signalcontrols the n−1 switching units on the transmission lines of the firstto (2^(n)/2−1)-th resistors to be turned on or off, which selects one ofGamma voltages to connect to the output terminal; when the voltageselecting module receives a second control signal and the selectingsignal, the selecting signal controls the n−1 switching units on thetransmission lines of the (2^(n)/2+1)-th to 2^(n)-th resistors to beturned on or off, which selects one of Gamma voltages to connect to theoutput terminal.

Wherein, in the reference voltage module, the first reference voltage isconnected to the ground through a first voltage dividing resistor and asecond voltage dividing resistor which are connected in series, thesecond reference voltage is connected between the first voltage dividingresistor and the second voltage dividing resistor, the resistance valuesof the first voltage dividing resistor and the second voltage dividingresistor are equal.

Wherein, the switching units are MOS transistors.

Wherein, n is a value of 10.

The another object of the present invention is to provide a sourcedriving module, which drives a pixel array unit, the pixel array unitcomprising a first pixel unit, a second pixel unit, and a third pixelunit, which correspondingly provides with a first pixel electrode, asecond pixel electrode, and a third pixel electrode, the source drivingmodule comprising a first Gamma voltage driving circuit, a second Gammavoltage driving circuit, and a third Gamma voltage driving circuit,which respectively provide Gamma voltage for the first pixel electrode,the second pixel electrode, and the third pixel electrode, wherein, theGamma voltage driving circuit is the driving circuit mentioned above.

The another object of the present invention is to provide a liquidcrystal panel, comprising:

-   a pixel array unit, which comprises a first pixel unit, a second    pixel unit, and a third pixel unit corresponding to a first color, a    second color, and a third color, the pixel array unit    correspondingly providing with a first pixel electrode, a second    pixel electrode, and a third pixel electrode;-   a gate driving module, which provides a scanning signal for the    pixel array unit; a source driving module, which provides a data    signal for the pixel array unit;-   wherein, the source driving module is the source driving module    mentioned above.

Comparing with the prior art, the Gamma voltage driving circuitaccording to the present invention can reduce the using amount ofdevice, reduce the difficulty of the design of driver IC and theproduction process, and save the costs.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view illustrating the structure of a liquidcrystal panel;

FIG. 2 is a schematic view illustrating a Gamma voltage driving circuitconnecting the module according to the prior art;

FIG. 3 is the circuit diagram of a Gamma voltage driving circuitaccording to the prior art, wherein the circuit can be divided into 8Gamma voltages by the reference voltage;

FIG. 4 is the circuit diagram of a Gamma voltage driving circuitaccording to the prior art, wherein the circuit can be divided into 1024Gamma voltages by the reference voltage; and

FIG. 5 is the circuit diagram of a Gamma voltage driving circuitaccording to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As mentioned above, in order to solve the existing problems of the priorart, the present invention provides a Gamma voltage driving circuit,which comprises: a voltage dividing resistor string, which comprises2^(n) resistors connected in series sequentially, used to divide areference voltage into 2^(n) Gamma voltages; wherein, n is an integernot less than 1; a reference voltage module, which provides thereference voltage for the voltage dividing resistor string; a voltageselecting module, which is used to selectively output one of the 2^(n)Gamma voltages.

Wherein, the reference voltage module comprises a first referencevoltage and a second reference voltage, the first reference voltage iscoupled to one end of the voltage dividing resistor string, the otherend of the voltage dividing resistor string is connected to the ground;the second reference voltage is coupled between the 2^(n)/2-th resistorand the (2^(n)/2+1)-th resistor, wherein, the value of the secondreference voltage is ½ of that of the first reference voltage; wherein,the voltage selecting module comprises 2^(n)−1 transmission lines, whichrespectively connects the voltage dividing nodes of the first to(2^(n)/2−1)-th resistors and the (2^(n)/2+1)-th to 2^(n)-th resistors inthe voltage dividing resistor string to a output terminal; and eachtransmission line is provided with n−1 switching units.

In the Gamma voltage driving circuit mentioned above, it provides tworeference voltages. Set the first reference voltage as a starting point,the first to (2^(n)/2−1)-th resistors in the voltage dividing resistorstring divide the voltage value between the first reference voltage andthe second reference voltage into 2^(n)/2 Gamma voltage. Therefore, eachtransmission line only needs n−1 switching units, which outputs one ofthe Gamma voltages every time according to the (n−1) bit binary codedmethod. The (2^(n)/2+1)-th to 2^(n)-th resistors divide the voltagevalue between the second reference voltage and the ground voltage into2^(n)/2 Gamma voltages. Therefore, each transmission line only needs n−1switching units, which outputs one of the Gamma voltages every timeaccording to the (n−1) bit binary coded method. Moreover, in the Gammavoltage driving circuit with higher grayscale precision, the referencevoltage needs to be divided into a lot of Gamma voltages. At this time,the two middle Gamma voltages (the voltages of the 2^(n)/2-th and the(2^(n)/2+1)-th resistors) are nearly equal, so that they can share oneof the Gamma voltage. In the present invention, it omits the Gammavoltage obtained from the 2^(n)/2-th resistor, instead, it uses theGamma voltage obtained from the (2^(n)/2+1)-th resistor, which furtherreduce the amount of the switch units. For the condition that thereference voltage needs to be divided into 2^(n) Gamma voltages, itneeds (2^(n)−1)*(n−1) switching units in the driving circuit accordingto the present invention, while it needs 2^(n)*n switching units in theGamma voltage driving circuit according to the prior art. The reducedamount of the switching units is 2^(n)+(n−1).

According to the Gamma voltage driving circuit mentioned above, it canreduce the using amount of device, reduce the difficulty of the designof driver IC and the production process, and save the costs.

The embodiment of the present invention is further illustratedaccompanying with the drawings as follows.

The present embodiment takes n=10 as example to illustrate. It should benoted that the technical solution of the present invention is notlimited thereto.

Referring to FIG. 5, the Gamma voltage driving circuit according to thepresent embodiment comprises:

-   a reference voltage module 10, which provides reference voltage for    the voltage dividing resistor string 20; a voltage dividing resistor    string 20, which comprises 1024 resistors connected in series    sequentially, used to divide a reference voltage into 1024 Gamma    voltages; a voltage selecting module 30, which is used to    selectively output one of the 1024 Gamma voltages;-   wherein, the reference voltage module 10 comprises a first reference    voltage Vref1 and a second reference voltage Vref2, the first    reference voltage Vref1 is coupled to one end of the voltage    dividing resistor string 20, the other end of the voltage dividing    resistor string 20 is connected to the ground; the second reference    voltage Vref2 is coupled between the 512-th resistor and the 513-th    resistor in the voltage dividing resistor string 20, wherein, the    Vref2=½Vref1;-   wherein, the voltage selecting module 30 comprises 1023 transmission    lines, which respectively connects the voltage dividing nodes of the    first to 511-th resistors and the 513-th to 1024-th resistors in the    voltage dividing resistor string 20 to a output terminal; and each    transmission line is provided with 9 switching units 301; it should    be noted that, in the present embodiment, the two middle Gamma    voltages (the voltages of the 512-th and the 513-th resistors) are    nearly equal, so they can share one of the Gamma voltage. In the    present invention, it omits the Gamma voltage obtained from the    512-th resistor, that is, the Gamma voltage obtained from the 512-th    resistor is not connected to the output terminal, instead, it uses    the Gamma voltage obtained from the 513-th resistor, which further    reduces the amount of the switch units.

In the present embodiment, the relationship of Vref2=½Vref1 is achievedthrough the two voltage dividing resistors 101 and 102. The firstreference voltage Vref1 is connected to the first voltage dividingresistor 101, the second voltage dividing resistor 102 is connected withthe first voltage dividing resistor 101 in series, the other end of thesecond voltage dividing resistor 102 is connected to the ground, thesecond reference voltage Vref2 is connected between the first voltagedividing resistor 101 and the second voltage dividing resistor 102, andthe resistance value of the first voltage dividing resistor 101 and thesecond voltage dividing resistor 102 are equal, so that Vref2=½Vref1.

In the present embodiment, the 1024 resistors in the voltage dividingresistor string 20 are equivalent resistance. The switching units 301connected on the transmission line are MOS transistors.

In the Gamma voltage driving circuit mentioned above, in the voltagedividing resistor string 20, set the first reference voltage Vref1 as astarting point, the first to 512-th resistors divide the voltage valuebetween Vref1˜Vref2 into 512 Gamma voltage; the 513-th to 1024-thresistors divide the voltage value between Vref2˜V0 (V0 refers to groundvoltage) into 512 Gamma voltage.

The Gamma voltage driving circuit according to the present embodimentfurther comprises a control module (not shown), which is used to providea control signal and a selecting signal for the voltage selecting module30. The control signal connects the selecting signal to the switchingunits between the first to the 512-th resistors or the switching unitsbetween the 513-th to the 1024-th resistors. The selecting signalcontrols the switching units to be turned on or off to select one of theGamma voltages.

When the voltage selecting module 30 receives a first control signal,the selecting signal connects to the switching units 301 on thetransmission lines of the first to 512-th resistors and controls theswitching units 301 to be turned on or off, which selects one of theGamma voltages formed from the first to 512-th resistors to connect tothe output terminal; when the voltage selecting module 30 receives asecond control signal, the selecting signal connects to the switchingunits 301 on the transmission lines of the 513-th to 1024-th resistorsand controls the switching units 301 to be turned on or off, whichselects one of the Gamma voltages formed from the 513-th to 1024-thresistors to connect to the output terminal.

On the transmission lines corresponding to the first to 512-thresistors, each switching unit has two states of turning on and off. Allcombinations of the switching units constitute 512 9 bit binary code,which exactly corresponds to 512 Gamma voltages V1˜V512 sequentially.When the selecting signal corresponds to one binary code, it outputs acorresponding Gamma voltage. Similarly, on the transmission linescorresponding to the 513-th to 1024-th resistors, each switching unithas two states of turning on and off. All combinations of the switchingunits constitute 512 9 bit binary code, which exactly corresponds to 512Gamma voltages V513˜V1024 sequentially. When the selecting signalcorresponds to one binary code, it outputs a corresponding Gammavoltage. It should be noted that, if the selecting signal corresponds tothe V512, the control module connects to the corresponding transmissionline of the 513-th resistor and outputs the V513 to the output terminal.

As mentioned above, in the condition of dividing the reference voltageinto 1024 Gamma voltages, the driving circuit according to the presentembodiment uses 1023 transmission lines. Each transmission line provideswith 9 MOS transistors, which totally need 9207 MOS transistors.However, the Gamma voltage driving circuit according to the prior artneeds 10240 MOS transistors, which reduces 1033 MOS transistors.According to the Gamma voltage driving circuit with higher grayscaleprecision, that is, n is a higher value, the technical solutionaccording to the present invention has a greater advantage.

The present embodiment further provides a source driving module, whichdrives a pixel array unit, the pixel array unit comprising a first pixelunit, a second pixel unit, and a third pixel unit (corresponding to thecolor of red, green, and blue), which correspondingly provides with afirst pixel electrode, a second pixel electrode, and a third pixelelectrode, the source driving module comprising a first Gamma voltagedriving circuit, a second Gamma voltage driving circuit, and a thirdGamma voltage driving circuit, which respectively provide Gamma voltagefor the first pixel electrode, the second pixel electrode, and the thirdpixel electrode, wherein, the Gamma voltage driving circuit is thedriving circuit mentioned above.

The present embodiment further provides a liquid crystal panel,comprising:

-   a pixel array unit, which comprises a first pixel unit, a second    pixel unit, and a third pixel unit corresponding to a first color, a    second color, and a third color (red, green, and blue), the pixel    array unit correspondingly providing with a first pixel electrode, a    second pixel electrode, and a third pixel electrode;-   a gate driving module, which provides a scanning signal for the    pixel array unit;-   a source driving module, which provides a data signal for the pixel    array unit;-   wherein, the source driving module is the source driving module    mentioned above.

In summary, the Gamma voltage driving circuit according to the presentinvention can reduce the using amount of device, reduce the difficultyof the design of driver IC and the production process, and save thecosts.

It needs to notice that, in this article, the relational terms such asfirst and second is only used to distinguish one entity or operatinganother entity or an operation, it is not necessary to require or implythat there exists any such relationship or sequence between the entityand operation. Besides, the terms “comprise,” “include,” or any othervariation are intended to cover a non-exclusive inclusion, therebymaking that comprising a series of process, method, materials orapparatus of element not only comprise those elements, but also compriseother elements not expressly listed, or also comprise such inherentelements of process, method, materials or apparatus. In the absence ofmore restrictive conditions, limiting the elements by the statement“comprises a . . . ”, it doesn't exclude that it also exists otheridentical elements in comprising the process, method, materials orapparatus of element.

The preferred embodiments of the present invention have been described.It should be noted that, for those having ordinary skills in the art,any deduction or modification according to the present invention isconsidered encompassed in the scope of protection defined by the claimsof the present invention.

What is claimed is:
 1. A Gamma voltage driving circuit, used to generatemultiple Gamma voltages, comprising: a voltage dividing resistor string,which comprises 2^(n) resistors connected in series sequentially, usedto divide a reference voltage into 2^(n) Gamma voltages; wherein, n isan integer not less than 1; a reference voltage module, which providesreference voltage for the voltage dividing resistor string; a voltageselecting module, which is used to selectively output one of the 2^(n)Gamma voltages; wherein, the reference voltage module comprises a firstreference voltage and a second reference voltage, the first referencevoltage is coupled to one end of the voltage dividing resistor string,the other end of the voltage dividing resistor string is connected tothe ground; the second reference voltage is coupled between the2^(n)/2-th resistor and the (2^(n)/2+1)-th resistor, wherein, the valueof the second reference voltage is ½ of that of the first referencevoltage; wherein, the voltage selecting module comprises 2^(n)−1transmission lines, which respectively connects the voltage dividingnodes of the first to (2^(n)/2−1)-th resistors and the (2^(n)/2+1)-th to2^(n)-th resistors in the voltage dividing resistor string to a outputterminal; and each transmission line is provided with n−1 switchingunits, wherein, the voltage dividing node between the 2^(n)/2-thresistor and the (2^(n)/2+1)-th resistor is not directly connected toall the transmission lines.
 2. The Gamma voltage driving circuit asclaimed in claim 1, wherein, in the voltage dividing resistor string,the first to (2^(n)/2−1)-th resistors divide the voltage value betweenthe first reference voltage and the second reference voltage into2^(n)/2 Gamma voltages; the (2^(n)/2+1)-th to 2^(n)-th resistors dividethe voltage value between the second reference voltage and the groundvoltage into 2^(n)/2 Gamma voltages.
 3. The Gamma voltage drivingcircuit as claimed in claim 2, wherein the 2^(n) resistors areequivalent resistance.
 4. The Gamma voltage driving circuit as claimedin claim 2, wherein the driving circuit further comprises a controlmodule, which is used to provide a control signal and a selecting signalfor the voltage selecting module; when the voltage selecting modulereceives a first control signal and the selecting signal, the selectingsignal controls the n−1 switching units on the transmission lines of thefirst to (2^(n)/2−1)-th resistors to be turned on or off, which selectsone of Gamma voltages to connect to the output terminal; when thevoltage selecting module receives a second control signal and theselecting signal, the selecting signal controls the n−1 switching unitson the transmission lines of the (2^(n)/2+1)-th to 2^(n)-th resistors tobe turned on or off, which selects one of Gamma voltages to connect tothe output terminal.
 5. The Gamma voltage driving circuit as claimed inclaim 1, wherein, in the reference voltage module, the first referencevoltage is connected to the ground through a first voltage dividingresistor and a second voltage dividing resistor which are connected inseries, the second reference voltage is connected between the firstvoltage dividing resistor and the second voltage dividing resistor, theresistance values of the first voltage dividing resistor and the secondvoltage dividing resistor are equal.
 6. The Gamma voltage drivingcircuit as claimed in claim 4, wherein, in the reference voltage module,the first reference voltage is connected to the ground through the firstvoltage dividing resistor and the second voltage dividing resistor whichare connected in series, the second reference voltage is connectedbetween the first voltage dividing resistor and the second voltagedividing resistor, the resistance values of the first voltage dividingresistor and the second voltage dividing resistor are equal.
 7. TheGamma voltage driving circuit as claimed in claim 1, wherein theswitching units are MOS transistors.
 8. The Gamma voltage drivingcircuit as claimed in claim 7, wherein n is a value of
 10. 9. A sourcedriving module, which drives a pixel array unit, the pixel array unitcomprising a first pixel unit, a second pixel unit, and a third pixelunit, which correspondingly provides with a first pixel electrode, asecond pixel electrode, and a third pixel electrode, the source drivingmodule comprising a first Gamma voltage driving circuit, a second Gammavoltage driving circuit, and a third Gamma voltage driving circuit,which respectively provide Gamma voltage for the first pixel electrode,the second pixel electrode, and the third pixel electrode, wherein theGamma voltage driving circuit comprises: a voltage dividing resistorstring, which comprises 2^(n) resistors connected in seriessequentially, used to divide a reference voltage into 2^(n) Gammavoltages; wherein, n is an integer not less than 1; a reference voltagemodule, which provides reference voltage for the voltage dividingresistor string; a voltage selecting module, which is used toselectively output one of the 2^(n) Gamma voltages; wherein, thereference voltage module comprises a first reference voltage and asecond reference voltage, the first reference voltage is coupled to oneend of the voltage dividing resistor string, the other end of thevoltage dividing resistor string is connected to the ground; the secondreference voltage is coupled between the 2^(n)/2-th resistor and the(2^(n)/2+1)-th resistor, wherein, the value of the second referencevoltage is ½ of that of the first reference voltage; wherein, thevoltage selecting module comprises 2^(n)−1 transmission lines, whichrespectively connects the voltage dividing nodes of the first to(2^(n)/2−1)-th resistors and the (2^(n)/2+1)-th to 2^(n)-th resistors inthe voltage dividing resistor string to a output terminal; and eachtransmission line is provided with n−1 switching units, wherein, thevoltage dividing node between the 2^(n)/2-th resistor and the(2^(n)/2+1)-th resistor is not directly connected to all thetransmission lines.
 10. The source driving module as claimed in claim 9,wherein, in the voltage dividing resistor string, the first to(2^(n)/2−1)-th resistors divide the voltage value between the firstreference voltage and the second reference voltage into 2^(n)/2 Gammavoltages; the (2^(n)/2+1)-th to 2^(n)-th resistors divide the voltagevalue between the second reference voltage and the ground voltage into2^(n)/2 Gamma voltages.
 11. The source driving module as claimed inclaim 10, wherein the 2^(n) resistors are equivalent resistance.
 12. Thesource driving module as claimed in claim 10, wherein the drivingcircuit further comprises a control module, which is used to provide acontrol signal and a selecting signal for the voltage selecting module;when the voltage selecting module receives a first control signal andthe selecting signal, the selecting signal controls the n−1 switchingunits on the transmission lines of the first to (2^(n)/2−1)-th resistorsto be turned on or off, which selects one of Gamma voltages to connectto the output terminal; when the voltage selecting module receives asecond control signal and the selecting signal, the selecting signalcontrols the n−1 switching units on the transmission lines of the(2^(n)/2+1)-th to 2^(n)-th resistors to be turned on or off, whichselects one of Gamma voltages to connect to the output terminal.
 13. Thesource driving module as claimed in claim 9, wherein, in the referencevoltage module, the first reference voltage is connected to the groundthrough a first voltage dividing resistor and a second voltage dividingresistor which are connected in series, the second reference voltage isconnected between the first voltage dividing resistor and the secondvoltage dividing resistor, the resistance values of the first voltagedividing resistor and the second voltage dividing resistor are equal.14. The source driving module as claimed in claim 9, wherein theswitching units are MOS transistors.
 15. The source driving module asclaimed in claim 14, wherein n is a value of
 10. 16. A liquid crystalpanel, comprising: a pixel array unit, which comprises a first pixelunit, a second pixel unit, and a third pixel unit corresponding to afirst color, a second color, and a third color, the pixel array unitcorrespondingly providing with a first pixel electrode, a second pixelelectrode, and a third pixel electrode; a gate driving module, whichprovides a scanning signal for the pixel array unit; a source drivingmodule, which provides a data signal for the pixel array unit; wherein,the source driving module comprising a first Gamma voltage drivingcircuit, a second Gamma voltage driving circuit, and a third Gammavoltage driving circuit, which respectively provide Gamma voltage forthe first pixel electrode, the second pixel electrode, and the thirdpixel electrode, wherein the Gamma voltage driving circuit comprises: avoltage dividing resistor string, which comprises 2^(n) resistorsconnected in series sequentially, used to divide a reference voltageinto 2^(n) Gamma voltages; wherein, n is an integer not less than 1; areference voltage module, which provides reference voltage for thevoltage dividing resistor string; a voltage selecting module, which isused to selectively output one of the 2^(n) Gamma voltages; wherein, thereference voltage module comprises a first reference voltage and asecond reference voltage, the first reference voltage is coupled to oneend of the voltage dividing resistor string, the other end of thevoltage dividing resistor string is connected to the ground; the secondreference voltage is coupled between the 2^(n)/2-th resistor and the(2^(n)/2+1)-th resistor, wherein, the value of the second referencevoltage is ½ of that of the first reference voltage; wherein, thevoltage selecting module comprises 2^(n)−1 transmission lines, whichrespectively connects the voltage dividing nodes of the first to(2^(n)/2−1)-th resistors and the (2^(n)/2+1)-th to 2^(n)-th resistors inthe voltage dividing resistor string to a output terminal; and eachtransmission line is provided with n−1 switching units, wherein, thevoltage dividing node between the 2^(n)/2-th resistor and the(2^(n)/2+1)-th resistor is not directly connected to all thetransmission lines.
 17. The liquid crystal panel as claimed in claim 16,wherein, in the voltage dividing resistor string, the first to(2^(n)/2−1)-th resistors divide the voltage value between the firstreference voltage and the second reference voltage into 2^(n)/2 Gammavoltages; the (2^(n)/2+1)-th to 2^(n)-th resistors divide the voltagevalue between the second reference voltage and the ground voltage into2^(n)/2 Gamma voltages; wherein, the 2^(n) resistors are equivalentresistance.
 18. The liquid crystal panel as claimed in claim 17, whereinthe driving circuit further comprises a control module, which is used toprovide a control signal and a selecting signal for the voltageselecting module; when the voltage selecting module receives a firstcontrol signal and the selecting signal, the selecting signal controlsthe n−1 switching units on the transmission lines of the first to(2^(n)/2−1)-th resistors to be turned on or off, which selects one ofGamma voltages to connect to the output terminal; when the voltageselecting module receives a second control signal and the selectingsignal, the selecting signal controls the n−1 switching units on thetransmission lines of the (2^(n)/2+1)-th to 2^(n)-th resistors to beturned on or off, which selects one of Gamma voltages to connect to theoutput terminal.
 19. The liquid crystal panel as claimed in claim 16,wherein the switching units are MOS transistors.
 20. The liquid crystalpanel as claimed in claim 19, wherein n is a value of 10.